Process for the manufacture of phosphates of the alkali and alkaline earth metals and of magnesium



Patented Sept. 5, 19.33.

PROCESS FOR THE PHOSPHATES OF ALKALINE- EARTH MAGNESIUM may micim' or run ALKALI AND METALS AND or Pi-istoupil, Aussig on the Elbe,

vaki v Czechoslo a No Drawing. Application March 9,1931, Serial No. 521,397, and in 1930 Czechoslovakia Math 15,

I '1 Claims. (01. 23-106) The present invention relates to a process for the production ofphosphates of the alkali and alkaline earth metals and of magnesium having a'higher P205 content than the metaphosphates,

. and'to the products obtained thereby. In order to obtain the new preparations the corresponding metaphosphates are treated with phosphorus pentoxide at an elevated temperature. The proc- .ess may be carried out, for example, by fusing together phosphorus pentoxide in its high-boiling, amorphous or glassy form with the corresponding metaphosphate. There is then ob tained a glassy mass the constitution of which has not yet been established. If, for example, 1 molecule P205 is, fused togethekvvith 1 molecule of calcium metaphosphate, there is formed when the melt solidifies a glassy mass which, surprisingly, is not hygroscopicp Similar products are formed by fusing together phosphorus pentoxide with other metaphosphates, for example with the metaphosphates of magnesium and of the alkali metals. l

' Instead of fusing together amorphous phosphorus pentoxide withthe metaphosphates, which is troublesome to carry out, phosphorus pentoxide vapour may be used as the starting material for the production of the new preparations by causing it to react onthe metaphosphates at an elevated temperature. Preferably, the phosphorus pentoxide vapour is, formed by the combustion of elemental phosphorus and the heat of combustion is made useof for maintaining the reaction with the-.metaphosphates. This method of L carrying out the process is particularly advan tageous since it enables the phosphorus-containing gases, which are formed in the manufacture of phosphorus by the reduction of phosphates,

to be directly utilized. For this purpose the phosphorus contained .in the phosphorus furnace gases is burnt in known manner to P205 and the heat resulting from this combustion is utilized for maintaining the reaction with the metaphosphate. The available amount of heat can also be 5 s ill further increased by fully utilizing the 00- content of the phosphorus furnace gases for the development of heat. 1

Preparations with different contents of P205 can be manufactured ,by the methodadescribed.

4 5 Thus, for example the proportion of Ca0:Pz05

in the calcium-phosphoric acid preparations obtained by the action of phosphorus pentoxide vapour on calcium metaphosphate may be between 1:1 to 1:2. In'the same way prepara- 5'5 tions :are obtained from' alkali-metaphosphates metaphosphate. The speed of the stream gas into was almost completely dissolved after stirring for which exhibit a still higher proportion of P205 to metal.

Example 1 A Pz05-containingvapour or a PzOs-containing gas is introduced, in as fine a' state of distribution as is conveniently practicable, at a tem perature'of 1100-12.00 C. intoa melt of calcium of gas should be regulated according to its content of P205 and according to the depth of the, melt. Since it is quickly taken up the speed may be considerable. in this way with quantitative and rapid absorption there, can be obtained in the ultimate product a molecular proportion up to 1Ca0 2P205. If diluted P205 vapour be employed, such as is obtained for example by the combustion of phosphorus furnace gas, a molecular proportion of 1CaO:1.5P2O5 is still easily obtained. Instead, of introducing th Pzos-containing the metaphosphate m It, the melt can be allowed to trickle or flow through a'shaft charged with filling materials in a direction counter to that of the gas. r

Ewample 2 A melt of sodium metaphosphate is treated with P205 vapour or Pros-containing gas at 600-800" C., in a similar manner as in Example 1." The products obtained are still richer in phosphoric, acid than the corres onding calcium prepara tions. By using undil ted P205 vapour preparations can be obtained with complete and quick absorptionof the P205 in which, for example,

the molecular proportion lNaaOtBPzOs is exceeded.

The new preparations, in view of their composition, are particularly suitable for use as fertilizers. They have a P205 content which can be increased to more. than 80%, and their solubility is satisfactory for fertilizing purposes. Thus for example a preparation having a composition irrwhich the proportion Ca0:Pz05--l:1 /2

about two days in cold water. A particular advantage of the new preparations is that, unlike free phosphoric acid and many phosphates, they are not hygroscopic and consequently possess great covering or spreading-power. The solubility gcan moreover be considerably increased without impairing their covering power, by subjecting the highly heated, preferably molten mass to quipk cooling or quenching, care being preferably taken that a large superficial area is p formed. The quenching may be effected for example by dropping the melt on to cold iron plates or by allowing it to flow into cold water.

1. Process for the production of phosphates of the alkali and alkaline earth metals and of magnesium having a higher P205 content than the metaphosphates which comprises treating a metaphosphate of one of-the said metals with phosphorus pentoxide at glowing heat.

2. Process for the production of phosphates of the alkali and alkaline earth metals and of magnesium having a higher P205 content than the metaphosphates which comprises fusing the amorphous, i. e. glassy, modification of phosphorus pentoxide with a metaphosphate of one of said metals. a

3. Process for the production of phosphates of the alkali and alkaline earth metals and of magnesium .having a higher P205 content than the metaphosphates which comprises treating a metaphosphate of one of the said metals with phosphorus pentoxide vapour at glowing heat.

4. Process for the production of phosphates of the alkali and alkaline earth metals and of magnesium having a higher P205 gontent than the metaphosphates which comprises burning elemental phosphorus to form phosphorus p'entoxide oeaeea treating a metaphosphate of one of said metals with the phosphorus pentoxide vapour formed at glowing heat and using the heat of combustion to maintain the reaction temperature.

5. Process for the production of phosphates of the alkali and alkaline earth metals and of magnesium having a higher P205 content than the metaphosphates which comprises treating a metaphosphate of one of the said metals with phosphorus pentoxide at glowing heat and rapidly cooling the product formed.

6. Process for the production ofphosphates'cf the alkali and alkaline earth metals and of magnesium having a higher P205 content than the metaphosphates which comprises fusing the amorphus, i. e. glassy, modification of phosphorus pentoxide with a metaphosphate of one of said metals, and rapidly cooling the product formed.

7. Process for the production of phosphates of the alkali and alkaline earth metals and of magne'sium having a higher P 05 content than the metaphosphates which comprises treating a metaphosphate of one of the said metals with will 

